Recently, vacuum packing, as well-known, has been used for keeping food stuffs long. Especially in the United States of America, vacuum packing is largely effective for transporting butcher's meat without its becoming tainted from the slaughter-house in the inland area, to the cities or to foreign countries. Therefore, many vacuum packers which are used only for packing butcher's meat have hitherto been invented, for example, as disclosed in U.S. Pat. Nos. 3,780,486 and 3,958,391. These patents disclose vacuum packing systems which place on a table the butcher's meat wrapped by a plastic film or bag, cover it by a chamber, and exhaust air therefrom, thereby carrying out vacuum packing. Such packers for exclusive use of meat, however, even when intended to vacuum-pack juicy objects, such as pickles, cannot lay them on the table without leaking water. Even if the bag is kept upright on the table by use of a jig, the mouth of the bag is subjected to distortion to lower the sealing accuracy for the bag. As a result, it is very difficult for packer developed for exclusive use of meat to vacuum-pack such pickles. From the first, the juicy contents, such as pickles, have been canned or bottled and have never been vacuum-packed by use of bags of low material cost in comparison with cans or bottles for the aforesaid reason.
On the other hand, U.S. Pat. No. 3,982,376 discloses a rotary packer for packing juicy objects in a bag, but not by vacuum packing. This packer has numerous pairs of clamps fixed to a long endless chain, and disposes, along the path of the chain, units for feeding bags, containing therein objects to be placed, and sealing the bag's mouth, so that the bags are supplied one by one by the bag feed unit. The while being supported in suspension by pairs of clamps, are transported by the chain to receive the objects to be packed, and then a sealing-weld is effected at the mouth of each bag. If vacuum chambers corresponding in number to the pairs of clamps are incorporated into this packer, the packer can perform of vacuum packing, but vacuum chambers are expensive to produce. Thus, to provide an equal number of vacuum chambers and clamp pairs would be quite expensive. In other words, in the section of the apparatus wherein bags are fed to the clamps and wherein the bags are filled, the chambers should be open, whereby the vacuum chambers are superfluous during this part of the operation.